Pratik Dhungana(BGE/070)
Survey Officer
Remote Sensing and Photogrammetry Section
Survey Department, Kathmandu
First of all, what is a map?
ï‚§ Map:
ï‚§ A scaled, simplified and symbolized representation of whole or part of earth via the
method of projection.
ï‚§ All maps are falsified (distorted) representation of reality, but good maps are those
where falsification is purposeful and meaningful
ï‚§ Cartography:
ï‚§ The art and science of map making
ï‚§ Topography:
ï‚§ Representation of land form and the features on land surface
ï‚§ Topographic map:
ï‚§ A 2-D representation of the earth's 3D landscape, where details of topography, artificial
and natural features are accurately represented
ï‚§ Extremely important for planning and implementing engineering and development
projects
ï‚§ It shows natural features like waterbodies, streams, ridges, forests, hills, mountains etc
ï‚§ Mand-made features like road network, utility lines, various types of religious and
functional buildings etc
ï‚§ Additional information like place and feature names
ï‚§ Topography is represented with the help of contours
ï‚§ Base map
ï‚§ a map showing features of different themes and thus serves as a base to derive various
thematic maps
ï‚§ Topographic maps of Nepal:
 Prepared by the Survey Deparment (SD) of Nepal—the only National Mapping
Organization (NMO)
ï‚§ Scale of 1:25K, 1:50K
ï‚§ Prior 1989, small scale topographic maps were prepared with
international support and cooperation.
ï‚§ 1930
ï‚§ Scale of 1 inch = 4 mile
ï‚§ 26 map sheets covering whole Nepal made by Survey of India.
ï‚§ 1950
ï‚§ Scale of 1: 250000
ï‚§ 17 map sheets made by US Army
ï‚§ 1970
ï‚§ Scale of 1 inch = 1 mile
ï‚§ 266 map sheets covering whole Nepal made by Survey of India.
ï‚§ 1977
ï‚§ Scale of 1:200000
ï‚§ Map Sheets covering whole Nepal made by Russian Government
ï‚§ 1989-1992
ï‚§ Lumbini Zone Mapping Project
ï‚§ 81 map sheets covering Lumbini Zone of Nepal in a scale of 1:25000
ï‚§ Prepared by Survey Department, Nepal with technical and financial
support of Government of Japan through Japan International
Cooperative Agency (JICA)
ï‚§ 1992-1996
ï‚§ Eastern Nepal Topographic Mapping Project
ï‚§ 255 map sheets in a scale of 1:25000 for tarai and middle mountains
and 37 map sheets in a scale of 1:50000 for high mountains and
himalayan region covering eastern Nepal .
ï‚§ Prepared by Survey Department, Nepal with technical and financial
support of Government of Finland through Finnish International
Development Agency (FINNIDA)
ï‚§ 1996-2001
ï‚§ Western Nepal Topographic Mapping Project
ï‚§ 254 map sheets in a scale of 1:25000 for tarai and middle mountains
and 79 map sheets in a scale of 1:50000 for high mountains and
himalayan region covering western Nepal except Lumbini zone.
ï‚§ Prepared by Survey Department, Nepal with technical and financial
support of Government of Finland through Finnish International
Development Agency (FINNIDA)
ï‚§ In 2001, topographic mapping of whole Nepal in a scale of
1:25000 and 1:50000 was completed.
ï‚§ Total of 706 map sheets including 590 map sheets in 1:25000
scale and 116 map sheets of 1:50000 scale.
1 inch = 4 mile
1: 250000
1 inch = 1 mile
1:200000
ï‚§ From 1989 to 2001traditional methods were used.
ï‚§ Aerial Photography
ï‚§ Aerial Photographs of 1989 for Lumbini zone Mapping Project
ï‚§ Aerial Photographs of 1992 for Eastern Nepal Mapping Project
ï‚§ Aerial Photographs of 1996 for Western Nepal Mapping Project
ï‚§ Stereo pair photographs covering entire mapping area were
collected
ï‚§ Stereoscopic Feature Extraction
ï‚§ Aerial Triangulation and Orientation image on stereo plotter for the
stereoscopic vision
ï‚§ Stereoscopic vision enables the 3D visualization in stereo pair
ï‚§ Plotting line features, polygon features, point features, and
contours.
Stereoplanigraph, Kelsh or PG-2
stereoplotter (Figure 3) (USGS,
1960).
• National Topographic Database(NTDB) is prepared
from scanned topographic maps prepared under
LMP, ENTMP and WNTMP.
• Georeferencing of Scanned Map sheet
• Onscreen Digitization
• Result: Digital topographic database
Preparation of National Topographic Database
• Acquire Images for target area
• Select most recent images with minimum cloud coverage
• Select suitable well distributed control points in images,
preferably in overlapping areas of multiple images
• Make use of existing topographic maps, Images and
sources like OSM and GoogleMaps for planning
• Orthorectification using corresponding rpc file and ALOS-
PALSAR DEM, to remove distortion due to tilt and terrain.
• Pansharpening of high resolution panchromatic image with low
resolution multispecral image to obtain high resolution
multispectral image.
• Georeferencing of pansharpened image with ground control
points obtained via DGPS.
• Update existing NTDB digital database based on georeferenced
image.
• Features are extracted by onscreen digitization and categorized
as per specification, based of image.
• Only planimetric details are taken. These features are to be
verified and modified as per field verification.
• Verification of Place names & texts and collection of
names to be changed.
• Verification of features category
• Collection of data on location, category and other
required characteristics of various infrastructures
• Necessary changes are made in the database as per field
verification.
• After database is updated, cartographic work begins.
• Symbolization of features by their categories and then
generalization .
• Making necessary alteration in position and size of annotations.
• Preparing map layout, test printing and necessary modification.
• After thorough checking, mass reproduction of map is done
using Computer to Plate technology.